Which of the following numbers is a factor of 192? ${7,8,9,11,13}$
Explanation: By definition, a factor of a number will divide evenly into that number. We can start by dividing $192$ by each of our answer choices. $192 \div 7 = 27\text{ R }3$ $192 \div 8 = 24$ $192 \div 9 = 21\text{ R }3$ $192 \div 11 = 17\text{ R }5$ $192 \div 13 = 14\text{ R }10$ The only answer choice that divides into $192$ with no remainder is $8$ $ 24$ $8$ $192$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $8$ are contained within the prime factors of $192$ $192 = 2\times2\times2\times2\times2\times2\times3 8 = 2\times2\times2$ Therefore the only factor of $192$ out of our choices is $8$. We can say that $192$ is divisible by $8$.